64 - Freie Mitteilung
16. Mai 2019, 13:45 - 15:15, Szenario 1, 5. OG


LIM protein ajuba promotes cancer cell proliferation and survival in hepatocellular carcinoma
N. Dommann1, J. Gavini1, D. Sánchez-Taltavull1, T. Brodie2, M. Medova1, M. Humbert1, M. Tschan1, D. Candinas1, D. Stroka1, Presenter: N. Dommann1 (1Bern, 2Zurich)

The LIM-domain protein Ajuba is a structural protein involved in the Hippo pathway and has a role in the maintenance of cell junctions, migration, differentiation, and proliferation. There are discrepancies in the literature as to whether it is a driver or suppressor of proliferation and little is known about it in the context of hepatocellular carcinoma (HCC). The aim of this study was to characterize Ajuba expression and function in HCC.
We screened 10 human liver cancer cell lines and primary tumors comparing them to control liver tissue or cultured primary human hepatocytes for protein and mRNA expression of Ajuba. The function of Ajuba was investigated by modulating its protein level with lentiviruses expressing shRNA targeted sequences (KD) or an overexpressing (OE) construct. The biological impact of Ajuba KD and OE transduced cells was tested in-vitro with various biological assays including RT2 Profiler PCR Arrays looking at Hippo pathway and cell cycle, Mass spectrometry of exogenous Ajuba and a 42-parameter panel for mass cytometry, and in an in-vivo syngeneic mouse tumor model.
Steady state levels of Ajuba mRNA in human liver cancer cell lines and primary tumors were significantly higher than in primary human hepatocytes or control liver tissue. Lentiviral transduction of HCC cell lines effectively knocked-down Ajuba protein resulting in a decrease of proliferation, migration, and colony formation, which coincided with a G2-phase cell cycle arrest and enhanced radiosensitivity. Previously published binding partners of Ajuba could be confirmed and new proteins were identified as Ajuba-binding using Mass spectrometry. Mass cytometry allowed the identification of new pathways in which Ajuba might be involved. Using a syngeneic tumor model in C57BL/6 mice, RIL-175 (mouse HCC cell line) transduced cells with knocked down Ajuba showed a significantly reduced tumor volume compared to controls.
Ajuba overexpression appears to be central to HCC cell proliferation and knock down reduces tumor growth.
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